1. Field of the Invention
The present invention relates to an ink composition and a method for recording an image, and in particular, to an ink composition comprising water, colorant and fine particles of resin and a method for recording an image using thereof.
2. Description of the Related Art
In recent years, the ink jet printing system has been well known as a recording method suitable as the output unit of information apparatus such as computers, etc., because of its low running costs, high image quality and because the easiness with which color printing can be achieved.
Aqueous dye solutions have conventionally been used in ink jet printing. There are, however, disadvantages. When ink discharged from a nozzle adheres to the surface of recording paper, the ink blots on the paper form dots larger than the particles of discharged ink, or the density of the recorded image is low, as is the image quality. And further, there is also the disadvantage that images tend to blot easily run when wet because of poor water resistance.
In order to solve these problems, (1) an ink composition in which a polyester particle colored with dye or pigment is dispersed, (2) an ink composition comprising an emulsion of non-crosslinked vinyl polymer as the main component, water-soluble polymer, dye or pigment and water, and (3) an ink jet printing method characterized by crosslinking on recording paper an ink composition comprising pigment, water-soluble or water-dispersible polyester or polyamide and crosslinking agent are disclosed in Japanese Patent Application Laid-open (JP-A) Nos. 6-340835 and 5-255628 and Japanese Patent Application Publication (JP-B) No. 7-47355, respectively.
However, the ink compositions disclosed in Japanese Patent Application Laid-open (JP-A) Nos. 6-340835 and 5-255628 cannot completely prevent ink blotting caused by capillary action of recording paper fibers or stop the ink from seeping into the recording paper. Thus, image density and water resistance are limited.
However, with the ink jet printing method described in Japanese Patent Application Publication (JP-B) No. 7-47355 the image layer was crosslinked and so image density was enhanced somewhat effectively. There were, however, concerns in the ink jet printing method described in Japanese Patent Application Publication (JP-B) No. 7-47355 for the stability of the ink since the crosslinking agent added is a reactive substance.
Since, in the inventions described in Japanese Patent Application Laid-open (JP-A) Nos. 6-340835 and 5-255628 and Japanese Patent Application Publication (JP-B) No.7-47355, the concentration of the solid content of resin in the ink composition is restricted to less than about 30% for production reasons and by physical properties, high image density could not be obtained without increasing the amount of ink per unit area of recording paper. Therefore, high image density could not be obtained with inkdrops of small diameter, i.e., with ink drops in small amounts required for realizing high image quality and high resolving power.